In most countries in Europe or America, the telephone company offers telephone users some special services, such as three-way calling, call waiting, etc. A telephone, by combining therewith an apparatus storing therein some function codes and some data corresponding to those function codes for accessing a function code, can be used for proceeding the special service.
Prior apparatuses capable of performing the similar function are various from one another in the market, dependent on by which company the apparatus was fabricated. Generally speaking, in the prior apparatus, the function codes and the data corresponding to the function codes are respectively accessed by pressing different keys. For example, suppose a call diverting service should be activated by a combination code of .sup.* A7654321#, wherein ".sup.* A", an initial code, and "#", a tail code, are both for requesting the call diverting service, and "7654321" is the desired phone number, e.g. a phone number in the user's office, a phone call should be automatically connected to, when there is a phone call directed to a phone number, e.g. a phone number at user's home, nobody will answer during a specific period of time, e.g. at work time. Due to the fact that each of the initial code, e.g. .sup.* A, the desired phone number, e.g. 7654321, and the tail code, e.g. #, is accessible by an individual key on the key pad of the telephone, the user has to accordingly press a first key for initiating the initial code, a second key for initiating the desired phone number, and a third key for initiating the tail code.
Therefore, the shortages of the prior apparatus are as follows:
1. Much more keys on the keypad of the telephone are required to perform the same amount of the services due to the fact that one key can only initiate one function code or one telephone number to be proceeded; PA1 2. Many troubles or inconveniences are existing to affect the operation of the telephone because the function codes and the data of the phone numbers stored in RAM are prone to get lost when the input electrical voltage is too low or the telephone set is turned off, or are easily re-entered and changed by another user unintentionally; and PA1 3. Big burdens are imposed to a user to memorize all informations required for operating the keys on the keypad.